Who was "Otis"?

Around 1930 there was an American advertising illustrator whose style was Moderne.  Aside from the featured product, the rest of the work was comprised of thin, simple lines and flat, lightly shaded areas.   Colors were black, white and grays.   These were signed "OTIS" with the signature partly hidden.

I found a number of such advertisements for Studebaker automobiles, and they are displayed below.   Interestingly, the same model year (1929), Studebaker also had more traditional-looking full color advertisements.  Perhaps placement of each style depended on the target magazine.

Unfortunately, I haven't been able to discover who Otis was.  Internet searches have turned up nothing useful so far.  One possible source is the New York Art Director Club annual for, say, 1930.   But copies are not convenient to where I live.

At this point, I can think of two possibilities.  One is Samual D. Otis (1888-1961) who did some commercial illustration.  Another is Otis Shepard (1894-1969), best known for his Wrigley's chewing gum advertising.  I wrote about him here.  Once upon a time I had a book about Shepard and his wife, but it was discarded during a downsizing a few years ago.  Sadly, it might have offered information on my Otis problem.

Perhaps a knowledgeable reader can provide an answer in Comments.

Click on images to enlarge.

Gallery

Here are seven 1929 Studebaker advertisements by Otis.

This ad is from 1930.